The polyol 1,3-propanediol (PDO) is a monomer useful in the production of a variety of polymers including polyesters, polyurethanes, polyethers and cyclic compounds. The polymers are ultimately used in fibers, films, coatings, composite materials, solvents, anti-freeze, copolyesters and other value-added applications. Although 1,3-propanediol may be produced by chemical synthesis, biological production via fermentation provides several advantages over chemical synthesis, including providing a sustainable, more environmentally friendly process. Fermentation using recombinantly-engineered bacteria using inexpensive carbon sources such as glucose or other sugars to produce 1,3-propanediol are known (see for example, U.S. Pat. No. 5,686,276, U.S. Pat. No. 6,358,716, U.S. Pat. No. 6,136,576, and U.S. Pat. No. 7,524,660). However, fermentative routes to producing 1,3-propanediol generate residual materials, such as acetate, which can compromise the quality of the polymers produced from this monomer. Consequently, the residual materials need to be removed from the 1,3-propanediol product by various separation methods, including ion exchange and distillation. The presence of acetate is particularly problematic because a high ion exchange capacity is required to reduce its concentration to acceptable levels.
Therefore, there is a need to reduce the amount of acetate produced during the production of 1,3-propanediol and other glycerol-derived products by fermentation to increase the capacity of the separation process required to obtain a product having acceptable purity levels. Additionally, acetate is a by-product known to inhibit bacterial growth (Lin et al., Appl. Microbiol. Biotechnol. 71:870-874, 2006), so a decrease in acetate production may lead to increased yields of 1,3-propanediol.